Fine structure of the down feather during its early development.
D000818:Animals; D002642:Chick Embryo; D004721:Endoplasmic Reticulum; D005241:Feathers / Q000166:cytology / Q000196:embryology*; D008722:Methods; D008854:Microscopy, Electron; D008928:Mitochondria; D009474:Neurons